Has you may know, Web sites hosted under Microsoft Azure Web Sites service are by default configure to timeout after idling 20 minutes (idleTimeout) and the application pool to restart every 29 hours (periodicRestart). This cause the web site to be slow for the first user accessing it.
I would like to know if the new "Always On" setting available on standard mode will prevent both situation from happening.
I found a few articles mentioning the feature, they are all very clear that the idle timeout will be avoided but none of them explicitly talks about the periodic restart:
One of the other useful Web Site features that we are introducing today is a feature we call “Always On”. When Always On is enabled on a site, Windows Azure will automatically ping your Web Site regularly to ensure that the Web Site is always active and in a warm/running state. This is useful to ensure that a site is always responsive (and that the app domain or worker process has not paged out due to lack of external HTTP requests).
Also the Azure Documentation is not very explicit:
Always On - By default, web sites are unloaded if they have been idle for some period of time. This lets the system conserve resources. You can enable the Always On setting for a site in Standard mode if the site needs to be loaded all the time. Because continuous web jobs may not run reliably if Always On is disabled, you should enable Always On when you have continuous web jobs running on the site.
http://www.windowsazure.com/en-us/documentation/articles/web-sites-configure/
Yes both of them will be prevented.
The default 29 hours periodicRestart was never on Azure Websites. That feature is an IIS feature that was enforced by WAS and was designed to run on a server level meaning restart all the worker processes on an IIS server. Both these things (WAS and IIS Server) don't apply to Azure Websites as WAS was the process management component of IIS and that was very specific to one box setup. Azure Websites uses a different process management component that doesn't have periodicRestart.
来源：https://stackoverflow.com/questions/21840983/will-always-on-setting-prevent-both-idletimeout-and-periodicrestart